<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>

<style>

    /* .box {
        width: 200px;
        height: 200px;
        background-color: red;
        padding-left: 30px;
        margin-top: 20px;
        border-style: solid;
        border-color: green;
        border-width: 5px;
    } */


    /* .box1 {
        width: 200px;
        height: 200px;
        background-color: blue;
        padding-left: 30px; 
        margin-top: 20px;
        border-style: solid;
        border-color: green;
        border-width: 5px;
    } */

    .box2 {
        width: 200px;
        height: 200px;
        background-color: blue;
        padding-left: 30px; 
        margin-top: 20px;
        border-style: solid;
        border-color: green;
        border-width: 5px;
        box-sizing:border-box;
    }
    


</style>


</head>
<body>

    <!-- <div class="box">这是一个盒子</div>
    <div class="box1">这是另一个盒子</div> -->
    <div class="box2">这是另一个盒子</div> 
    
</body>
</html>